UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON , D.C

. 20460 

## SEP 232014

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION


### MEMORANDUM
SUBJECT: BEAD Chemical Profile (BCP) for Registration Review: Oxadiazon (109001) 

### FROM: Sunil Ratnayake, Ph.D., Biologist 

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### TO: Biological Analysis Branch

# ~**~** l DonAtwood, Ph.D., Entomologist 

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# w-zv #'11;**~** Science Information and Analysis Branch Stephen Smearman, Economist

# ~t..I/'/J**~** Economic Analysis Branch Biological and Economic Analysis Division (7503P) Arnet Jones, Chief Biological Analysis Branch Diann Sims, Chief

# !9~~ Science Information and Analysis Branch Timothy Kiely, Chief

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# lu.-j Economic Analysis Branch Biological and Economic Analy ·s Divis' (7503P) Joel Wolf, Chemical Review Manager Re-evaluation Management and Implementation Branch 2 Pesticide Re-evaluation Division (7508P)
PeerReview Panel date: September 10, 2014

Page 1SUMMARY Oxadiazon was first registered in the U.S. in 1978. It is a selective herbicide applied as pre and early post-emergence treatments for the control ofmany annual broadleafand grass weeds. Major use sites ofthis chemical are established ornewly established bermudagrass, perennial ryegrass, fescue 

### turf, and various ornamentals, including landscape ornamental beds. There are no food orfeed, or anticipated food orfeed uses for oxadiazon. No agricultural usage data are available for this chemical and the highest non-agricultural usage ofthis chemical is on golf courses.


### INTRODUCTION The Biological and Economic Analysis Division (BEAD) Chemical Profile (BCP) provides an overview ofthe pest management roles and quantitative usage information for oxadiazon. The BCP includes summaries ofprevious BEAD products and available public and/or private use and usage data for oxadiazonto describe the role ofthis chemical inpestmanagement. Additional information onuse is available in the Oxadiazon Label Data Report provided in the public docket for this chemical. Information provided in this BEAD Chemical Profile (BCP) may be used by stakeholders (e.g., users and registrants), OPP risk assessors, and OPP risk managers, and the general public during the Registration Reviewprocess ofthis pesticide.


### AGRICULTURAL USE SITES There is no food orfeed, or anticipated food or feed uses for oxadiazon. The Registrant is not supporting any tolerances for oxadiazon in the United States and existing tolerances have been revoked. (EPA, 2008)


### NON-AGRICULTURAL USE SITES Oxadiazonis registered for commercial use on turfgrown in golfcourses and in areas such as apartment/condominium complexes, parks, athletic fields, playgrounds, and cemeteries. In addition, oxadiazon is used on sod farms and on conifer nurseries and landscapes (i.e. industrial sites, ornamental, roadside plantings, woody, ornamental shrubs, vines and trees, and herbaceous ornamentals).

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### FORMULATIONS AND APPLICATION METHODS Oxadiazon can be formulated as a granular, wettable powder, emulsifiable concentrate, water soluble packets, and mixed with fertilizer. Application is made by ground using spreader/granular appli

_ cator or calibrated sprayer.


### IDSTORY OF OXADIAZON AND BEAD PRODUCTS Oxadiazon was registered in 1978. A Phase Four generic data call-in (DCI) was issued in May of 1991. Due to additional data required under FIFRA as amended in 1988, the oxadiazonregistrant decided to no longer support food uses ofoxadiazon. On June 3, 2002, the Agency considered the FQPA safety finding to be met and counted the oxadiazon tolerances asreassessed. There are no CODEX, Canadian, or Mexicantolerances for oxadiazon residues. A search ofthe BEAD database for previous BEAD products for oxadiazon indicates that there are no records ofprior BEAD benefits assessments or emergency exemption requests for oxadiazon inthe last 10 years. Note that a lack ofemergency exemptionrequests does not indicate the relative importance ofthe chemical.


### OXADIAZON USAGE Agricultural Usage There are no agricultural uses for oxadiazon. 

### Non-Agricultural Usage Datafor oxadiazonuse onnon-agricultural sites is limited to BEAD proprietary data. As shown in Table 1, golfcourse is the primary non-agricultural use site with approximately 78% of oxadiazon usage. Table 1. Usage ofOxadiazon onVarious Non-agricultural Sites (2012)**Segp~ent** 1:. -

Golf Institutional Turf Landscape LCO Nursery/Greenhouse Turf Total 1Total maynot add due to roundmg. Source: Proprietary data, 2012 -**U~ag~ (lOOO**  

### lbs a.i.) 212

17 19 7 5 14 273 1

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### ..,BIOLOGICAL ASPECTS RELEVANT TO OXADIAZON Oxadiazonbelongs to the family ofprotox-inhibiting herbicides and the mode ofaction ofthis herbicide family is inhibition ofprotoporphyrinogen oxidase enzyme. Inhibition ofthis enzyme inplants lead to interfering ofchlorophyll production path way resulting in a breakdown ofplant tissues on exposure to light. Injury symptoms include wilting followed by necrosis and desiccation (Herbicide handbook, 2014). Foliar applications ofthis herbicide shows injury symptoms within 1to 2 days. Soil applied oxadiazon is readily absorbed by shoots ofemerging seedlings and root absorbtion ofseedlings is comparatively lesser than the shoot absorption. This herbicide accumulates in olderplantparts with little movement to the growing points.
ROLE OF OXADIAZON IN PEST MANAGEMENT Oxadiazon is a pre-emergence herbicide labeled for use onturfgrasses such as newly established bermudagrass, perennial ryegrass, and woody ornamentals (Herbicide Handbook, 2014). Oxadiazon controls most annual grasses and many small-seeded broadleafweeds. The potential for injury limits the use ofoxadiazon onzoysiagrass and St. Augustinegrass species. Oxadiazon can be safely used on dormant or actively-growing bermudagrass, bluegrass, perennial ryegrass, St. Augustinegrass, zoysiagrass and tall fescue. Oxadiazon fonnulations are not labeled for use onputting greens. Red fescue, bentgrass and centipedegrass are only marginally tolerant to oxadiazon. When applied as a pre-emergence treatment oxadiazon controls grass species such as crabgrass 

### (Digitatria spp.) goosegrass 

### (Eleusine indica), annual bluegrass 

### (Poa annua) and annual sedge 

### (Cyperus compressus). DATA NEEDS The Agency currently does not have important information on oxadiazon. Obtaining the following information for all registered non-agricultural sites may improve future assessments conducted bythe Agency related to the use and importance ofoxadiazon. Usage

• Total pounds active ingredient applied • Percent crop/site treated • Applicationrates·: typical and maximum • Frequency ofapplication by region ofthe country • Application Intervals by region ofthe country • Methods ofapplication • Target orniche pests • Efficacy information/productperformance

Page4REFERENCES EPA. 2008. Oxadiazon RED Fact Sheet. Available at: http:/ /www.epa.gov/oppOOOO 1/chem search/reg actions/reregistration/fs PC109001 20-Jun-08.pdf
. Accessed onJuly 2, 2014. Herbicide Handbook. 2014. Tenth Edition. Published by Weed Science Society ofAmerica. 810 E. lOth Street, Lawrence, KS 66044. Proprietary Data. 2004-2012. Proprietary Data. 2008-2012. Proprietary Data. 2012.

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